Pyrethroid compounds are widely used for the control of insect pests in agricultural areas as well as for structural pest control in urban areas. This class of pesticides is non-systemic and has contact and stomach action. Most pyrethroids act on the nervous system of insects, and disrupt the function of the neurons by interacting with sodium channels. Pyrethroids are highly nonpolar, have low water solubility, low volatility, high octanol-water partition coefficients, and have high affinity for soil and sediment particulate matter. As a result pyrethroids are easily adsorbed to the sediments of natural water systems and have low soil mobility. Pyrethroids in water solution tend to be stable at acid and neutral pH but become increasingly susceptible to hydrolysis under alkaline conditions. Pyrethroids can vary in their susceptibility to sunlight (e.g., see Rev. Environ. Contam. Toxicol. 2002; 174:49-170).
Because of their low water solubility, pyrethroids are currently formulated into various usable forms such as emulsifiable concentrates (ECs), liquid concentrate (SL), and suspension concentrates (SC) that use petroleum or non-petroleum based solvents along with anionic and non-ionic emulsifiers and stabilizers. Pyrethroids have also been formulated as water dispersible powders or granules (WPs or WGs) and soluble powders (SP) that use organic or inorganic carriers. These formulations are available as solid or liquid formulations with varying contents of active ingredient (low or high) that can be used as is or after dilution with water. As described below, while these formulations address some of the inherent challenges that are associated with pyrethroids there remains a need in the art for improved pyrethroid formulations.